10.4 Invoking guix hash

The guix hash command computes the hash of a file. It is primarily a convenience tool for anyone contributing to the distribution: it computes the cryptographic hash of one or more files, which can be used in the definition of a package (see Defining Packages).

The general syntax is:

guix hash option file ...

When file is - (a hyphen), guix hash computes the hash of data read from standard input. guix hash has the following options:

--hash=algorithm

-H algorithm

Compute a hash using the specified algorithm, sha256 by default.

algorithm must be the name of a cryptographic hash algorithm supported by Libgcrypt via Guile-Gcrypt—e.g., sha512 or sha3-256 (see Hash Functions in Guile-Gcrypt Reference Manual).

--format=fmt

-f fmt

Write the hash in the format specified by fmt.

Supported formats: base64, nix-base32, base32, base16 (hex and hexadecimal can be used as well).

If the --format option is not specified, guix hash will output the hash in nix-base32. This representation is used in the definitions of packages.

--recursive

-r

The --recursive option is deprecated in favor of --serializer=nar (see below); -r remains accepted as a convenient shorthand.

--serializer=type

-S type

Compute the hash on file using type serialization.

type may be one of the following:

none

This is the default: it computes the hash of a file’s contents.

nar

Compute the hash of a “normalized archive” (or “nar”) containing file, including its children if it is a directory. Some of the metadata of file is part of the archive; for instance, when file is a regular file, the hash is different depending on whether file is executable or not. Metadata such as time stamps have no impact on the hash (see Invoking guix archive, for more info on the nar format).

git

Compute the hash of the file or directory as a Git “tree”, following the same method as the Git version control system.

--exclude-vcs

-x

When combined with --recursive, exclude version control system directories (.bzr, .git, .hg, etc.).

As an example, here is how you would compute the hash of a Git checkout, which is useful when using the git-fetch method (see origin Reference):

$ git clone http://example.org/foo.git
$ cd foo
$ guix hash -x --serializer=nar .